POLYMER COATING OF WIRE USING A DIE-LESS DRAWING PROCESS

A process known as die-less wire drawing has been developed in which polymer melts are used as a pressure medium in a reduction unit of stepped bore geometry. The wire size is less than the bore of the reduction unit, eliminating a conventional die, and providing a combined deformation of the wire together with a polymer coating. Previous experimental investigations have shown significant percentages in reduction of area but polymer coating of poor adhesion to the drawn wire. The present experimental investigation compares the coating performance on copper wire with different types of polymer which vary in melt index and viscosity ranges. The results show that adhesion is good with polyamides and the quality of coat improved using a low melt index polyethylene. Significant reductions in area of wire were achieved but small variations in maximum reduction were measured with changes in the polymer melt. Temperature of the polymer and drawing speed had significant effects on both the reduction in area and quality of polymer coating on the wire.